Incinerator hot oil recovery system

ABSTRACT

An incinerator hot oil recovery system for use with an installation such as a multisection color printing press in which a heating medium such as oil is brought into heat exchange relationship with air at the installation to assist in drying material such as ink or the like and in which ink solvent contaminated air is to be carried away from the installation, in which system contaminant-laden air is exhausted from the press to the combustion chamber of an incinerator whereat the air is raised to a temperature at which the contaminants burn to harmless by-products and then the air is discharged to the atmosphere through a heat exchange relationship with oil to heat the same, which is then returned to the installation at which the heated oil is employed to heat the drying air and is then recirculated back to the incinerator heat exchanger. Various safety features are employed to obviate damage to the equipment and to minimize danger to the operating personnel.

United States Patent 1191 Villalobos et a1.

[4 1 Sept. 16, 1975 1 INCINERATOR HOT OIL RECOVERY SYSTEM [73] Assignee: AER Corporation, Ramsey, NJ.

[221 Filed: Aug. 13, 1974 [211 App]. No.: 497,106

[52] US. Cl 34/72; 34/86; 236/15 E; 110/8 R; 34/79 [51] Int. Cl. F23G 7/00; F26B 19/00 [58] Field of Search 110/8 R; 8 A, 18 R, 15 R; 34/68, 72, 32, 47, 48, 73, 79, 86; 431/5, 202; 236/15 E [56] References Cited UNITED STATES PATENTS 3,486,841 12/1969 Betz 34/68 3,511,224 5/1970 Porwancher... 110/8 R 3,601,900 8/1971 Erisman t 1 10/8 A 3,675,600 7/1972 Jones 110/8 R 3,728,797 4/1973 Worden, Sr. ct a1. 34/86 3,749,030 7/1973 Burden, Jr. et a1. 1 10/8 R 3,772,851 11/1973 Dufi'y 236/15 E 3,793,741 2/1974 Smith, Jr 34/68 Primary Examiner-John .1. Camby Assistant ExaminerHenry C. Yuen Atlorne Agent, or FirmShenier & OConnor 5 7 ABSTRACT An incinerator hot oil recovery system for use with an installation such as a multisection color printing press in which a heating medium such as oil is brought into heat exchange relationship with air at the installation to assist in drying material such as ink or the like and in which ink solvent contaminated air is to be carried away from the installation, in which system contaminant-laden air is exhausted from the press to the combustion chamber of an incinerator whereat the air is raised to a temperature at which the contaminants burn to harmless by-products and then the air is discharged to the atmosphere through a heat exchange relationship with oil to heat the same, which is then returned to the installation at which the heated oil is employed to heat the drying air and is then recirculated back to the incinerator heat exchanger. Various safety features are employed to obviate damage to the equipment and to minimize danger to the operating personnel.

18 Claims, 9 Drawing Figures PATENTED SEP 1 8 i975 sum '1 [1F 7 INCINERATOR HOT OIL RECOVERY SYSTEM BACKGROUND OF THE INVENTION There are known in the prior art installations in which a material which is supplied to a moving web or the like is required to be dried. For example, multisection color printing presses use heated air to dry the inks which are applied to the paper in the course of the printing operation. Inks which are employed in the printing operation incorporate various solvents, such as toluol, isopropyl acetate, isopropyl alcohol, methyl ethyl ketone and ethyl acetate. In the course of the drying operation the solvents are carried away with the drying air as contaminants. It is obvious that in a system of this type a source of energy is necessary to heat the drying air. Moreover, the contaminated air must be carried away from the press installation. If this contaminated air is discharged to the atmosphere without further treatment, it contributes to the pollution of the atmosphere.

We have invented an incinerator hot oil recovery sys tem which is especially adapted for use with an-installation in which drying air must be heated and in which contaminant-laden air must be disposed of. Our system disposes of contaminant-laden air without appreciably polluting the atmosphere. Our system eliminates the necessity for a separate source of heat for heating dry-. ing air. Our system makes use of the heat of combustion of contaminants to heat the air heating medium. Our system is extremely efficient for the result achieved thereby.

SUMMARY OF THE INVENTION One object of our invention is to provide an incinerator hot oil recovery system which is especially adapted for use in an installation in which drying air must be heated and in which contaminant-laden air must be disposed of.

Another object of our invention is to provide an incinerator hot oil recovery system which disposes of contaminant-laden air without polluting the atmosphere.

A further object of our invention is to provide an incinerator hot oil recovery system which eliminates the need for a separate source of energy to heat air drying oil at color press sections, for example.

A still further object of our invention is to provide an incinerator hot oil recovery system which is extremely efficient for the results achieved thereby.

Other and further objects of our invention will appear from the following description.

In general our invention contemplates the provision of a system in which cntaminant-laden air from a printing press or the like is exhausted to the combustion chamber of an incinerator at which the air temperature is raised to a point at which the contaminants burn to harmless by-products and in which the air is then exhausted to the atmosphere through a heat exchanger whereat it is brought into heat transfer relationship with oil which is circulated from the exchanger to an air heating system at the installation and back to the heat exchanger. Our system incorporates a number of safety features for preventing damage to the operating equipment and for minimizing danger to the operating personnel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of the incinerator and heat exchange portion of our incinerator hot oil recovery system.

FIG. 2 is a top plan view of the portion of the system shown in FIG. 1 with its relation to an installation such as a printing press being shown schematically.

FIG. 3 is an end elevation of the portion of our system illustrated in FIG. 1.

FIG. 4 is a schematic view of the hot oil heating system of our incinerator hot oil recovery system.

FIG. 5 is a schematic view of a portion of the pneumatic piping of our incinerator hot oil recovery system.

FIG. 6 is a schematic view of a further portion of the pneumatic system of our incinerator hot oil recovery system.

FIG. 7A is a schematic view of a portion of the elec trical control circuit which may be employed with our incinerator hot oil recovery system.

FIG. 7B is a schematic view of the remainder of the electrical control circuit which is used to control the operation of our incinerator hot oil recovery system.

FIG. 8 is a schematic view illustrating a lower explosion limit control arrangement which we apply to our incinerator hot oil recovery system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 to 3, our system to be described hereinbelow is especially adapted for use with a multicolor printing press shown schematically in FIG. 2 and indicated generally by the reference character 10, supported on the floor 12 of a plant. The press 10, which may be a rotogravure printing press, includes a plurality of sections, four sections of which we have indicated generally respectively by the reference characters l4, l6, l8, and 20. It will readily be appreciated that such a press may incorporate as many as nine sections or stations at which printing operations are carried out. Moreover, as is known in the art, each of these sections is supplied with drying air which may be heated by any suitable heat exchange device (not shown) so as to carry away as contaminants volatilized solvents used in the printing ink. Such solvents may. for example, be toluol, isopropyl acetate, isopropyl alcohol, methyl ethyl ketone. or ethyl acetate. For the purpose of containing the contaminant-laden air, each of the sections l4, l6, l8, and 20 is provided with a hood 22. All of the hoods are connected to a common return duct 24.

Our system includes a fume incinerator indicated generally by the reference character 26, which is supported, for example, on the roof 28 of the plant housing the printing installation. The incinerator 26 may be enclosed in a penthouse 30 located on the roof 28. The incinerator 26 includes a fan inlet duct 32 which receives the fumes from the common return duct 24. A fan 34 driven by a fan motor 36 carries the contaminant-laden air through the inlet 32 to a vertical duct section 38 leading into a transfer section 40 provided with turning vanes 42. The transfer section 40 leads into a horizontal duct section 44, the last two parts of which are connected by respective inlet ducts 46 and 48 to the duct burner feed section 50.

We arrange a low volume damper assembly indicated generally by the reference character 52 between the parts of section 44, to which inlets 46 and 48 are connected. Damper 52 is operated in a manner to be described hereinbelow to reduce the amount of contaminated air fed to the incinerator when desired. Preferably, we provide a manually-operated damper 53 between the outlet of the fan 34 and the duct section 38.

We provide our incinerator with two burner sections, one of which is indicated generally by the reference character 54, for raising the temperature of the contaminated air to a point at which the contaminants burn to harmless by-products. Preferably we select the burner assemblies to be such as will provide 16,500,000 Btu per hour at maximum rating. The assemblies, moreover, have a twenty-to-one turn-down ratio. As the contaminant-laden air passes by the burners 54, it enters the incineration chamber 56 of the fume incinerator 26. We provide the chamber 56 with a wall 58 constructed of refractory and block-type insulation .which will withstand the high temperature involved. The outer shell of the wall 58 is formed from Republic Cor-ten, which is the registered trademark of Republic Steel Corp. of Cleveland, Ohio for a low alloy, high strength steel having a high resistance to atmospheric corrosion. We provide the wall 58 with an outer skin 60 of aluminized steel which will cover the outside of the incinerator. A fan 62 driven by a motor 64 pressurizes the space between the skin sheet and the tank to a pressure slightly higher than that which exists inside the incinerator. The skin 60 forming this pressurized space provides an extremely good insulation. 1t prevents any high temperature air from escaping through pinholes" which may exist in the welds used to secure the outer wall covering plates.

t Air containing the harmless by-products of the combustion of the contaminants in the region below the burners 54 passes by a baffle 66 within the chamber 56. This air may then pass upwardly through a main stack 68 extending upwardly through the penthouse roof to pass harmlessly into the atmosphere. We provide the entry to the stack 68 with the damper assembly 70. Our assembly also includes an auxiliary stack 72 leading from the top of the combustion chamber through the penthouse roof to the atmosphere. We provide an auxiliary stack damper assembly 74 between the chamber and the auxiliary stack. A common operating member 76 is adapted to be actuated in a manner to be described hereinbelow to operate the damper assemblies 70 and 74 to by-pass the main stack when desired.

We position a heat exchanger 78 in the main stack 68 in order to bring the hot air carrying the by-products and passing up the stack into heat exchange relationship with the drying air heating oil which is circulated to the press in a manner to be described. Preferably, the heat exchanger provides a 4,620,000 Btu per hour waste heat recovery coil for 397 gallons per minute. An inlet pipe 80 is adapted to conduct the oil into the coil, while an outlet pipe 82 carries the oil back to the press.

Referring now to FIG. 4 of the drawings, we have illustrated the heating oil circulating system of our incinerator hot oil recovery system. A suitable tank 86 adapted to hold a supply of oil which is used as the heating medium for heating drying air at each of the sections, such as the section 14 of the press 10. For purposes of simplicity, in FIG. 4 we have illustrated in detail only the heating oil system associated with the sec tion 14. A transfer pump 94, which may be of the rotary gear type driven by a 2 HP. motor at 1200 r.p.m.,

4 draws the heating oil from tank 86 through a pair of gate valves 88 and 90 and delivers it to a line through a swing check valve 96 and a gate valve 98.

The circulating system includes an input or feed line 104 and a return line 106. We connect line 100 to the return line 106 by a connection l08. We provide a manually-operated 'gate valve 102 connected between feed line 104 and return line 106 and adapted to be opened'to by-pass the various sections of the press, if desired. Respective gate valves 110 and 112 connect pipes 82 and 80 to lines 104 and 106. A gate valve 114 is adapted to by-pass the pump 94. A first gate valve 1 15 is adapted to be opened to connect line 80 to valve 90 leading to the pump 94. A second gate valve 116 is adapted to be operated when the system is to be drained.

We connect line 100 to an expansion tank 1 18. Gate valves 120 and 122 connect a liquid level gauge 124 across expansion tank 118. A warm-up valve 126 is adapted to connect line 104 to the tank 118. A flowcontrol valve 128 and a pressure regulator 130 connect a tank 132 containing a pressurizing gas, such for example as nitrogen, to the expansion tank 118. We connect a combination pump controller and low level cutout 134 across the tank 118. A pressure-responsive switch 136 connected to the source of pressurizing gas by a line 138 is adapted to break in response to a predetermined pressure drop. A length of capillary tubing 142 conducts oil from the expansion tank 118 to a thermometer of any suitable type known to the art.

A first probe 144 associated with pipe 82 is adapted to operate an oil high temperature limit switch 146. A second probe 148 associated with pipe 82 actuates a temperature controller 150 which controls the operation of the dampers in the main and by-pass stacks of the incinerator 26. Respective vent valves 152, 154, and 156 connect pipe 82, expansion tank 118, and line 104 to a vent line 158 provided with a connection 160 leading to a non-spill venter.

We provide respective relief valves 162 and 164 assoeiated with pipe 82 and with the expansion tank 118. A line 166 connects the pipe 82 to a high-limit oil pressure switch 168 of the system.

We arrange a gate valve 170, the main circulating pump 172, and a globe valve 174 in series 'in the pipe 106. A gate valve 176, a standby pump 178, and a globe valve by-pass the main pump system, if for any reason it should become inoperative. Respective swing check valves 182 and 184 connect the outlets of the pumps '172 and 178 to a line 186 leading to the high-limit oil pressure switch 168.

Our system includes a by-pass loop indicated generally by the reference character 188, including a gate valve 190, a normally closed by-pass valve 192,'and a gate valve 193 connected in series between lines 104 and 106. A flow element 195 in line 106 supplies oil to a differential pressure cell transducer 194 to actuate a flow controller 196 to operate 'valve 192 normally to interrupt the by-pass loop 188. The oil system works with constant oil flow. Consequently, if the units of the press are not on or are throttled back, controller 196 opens valve 192 to complete the oil by-pass to maintain constant flow of oil.

The air heater of each of the press sections, such as the section 14, includes a coil 200 through which the heated oil passes to heat the drying air at the unit. A strainer 202, gate valve 204, control valve 206 and sec- 0nd gate valve 208 connect the upper end of the coil 200 to the feed line 104. A gate valve 210 and a swing check valve 212 connect the lower end of the coil to the return line 106. A probe 214 associated with the coil 200 actuates a temperature controller 216 which controls the operation of the valve 206 to regulate the flow of oil to the coil 200 in response to the temperature sensed by the sensor 214.

Referring now to FIG. 6, the pneumatic control system of our incinerator hot oil recovery system includes a source line 215 carrying compressed air at approximately 50 pounds per square inch minimum. A line 216 containing a filter 218 and pressure regulator 220 connects the source line to the input of the differential pressure cell transducer 194. An output line 222 connects the outlet of the transducer 194 to the control input of the flow controller 196. A line 230 containing a filter 224, a flow regulator 226, and a meter 228 applies pressure from the source 215 to the input terminal of controller 196. In response to the pressure on line 222, controller 196 supplies air under pressure to the actuating element of the flow control valve 192 through a line 232 to open the valve to complete the by-pass loop 188 in response to a predetermined change in pressure across the flow element 195.

A line 240 provided with a filter 234, a regulator 236, and a meter 238 provides input air pressure to the temperature controller 150. As is pointed out hereinabove, probe 148 conducts oil to the temperature controller 150 to operate the controller in such a way that the air pressure on the output line 242 is a measure of the temperature of the oil. We connect line 242 to the operator 244 which actuates a lever 246 to operate the common linkage 76 of the damper systems 70 and 74. When the temperature of the oil exceeds a predetermined value, controller 150 so regulates the pressure on line 242 that the dampers 70 tend to close and the dampers 74 to open.

The pneumatic control system includes a static pressure controller 248, the input of which is connected to line 240. A tap 250 in the intake line 32 leading to the fan 34 is connected to the control terminal of the controller 248. In response to this pressure, the controller 248 supplies an output pressure on a line 254 for actu ating an operator 256 adapted to position a lever 258 to operate a crank 260 connected to an inlet vortex damper 262 at the fan 34. We also provide a duct section 38 with a tap 264 leading to the exhaust fan air flow switch to be described hereinbelow.

Referring to FIG. 5, an air line 266 leading from the source line 215 of FIG. 6, includes a normally closed solenoid-operated pilot valve 268 for feeding air through a vent valve 272 and a shutoff valve 274 to the junction with a burner fuel inlet line 276. A gauge 270 is adapted to register the pressure at the outlet of valve 218. A regulator 280 conducts the mixture of burner gas and air to a safety shutoff valve 284 provided with a test cock 286. A vent line 288 connected to the outlet of valve 284 is normally closed by a blocking valve 290. We connect a low gas pressure switch 282 to the outlet of regulator 280. A blocking valve 292 connects valve 284 to the main shutoff valve 296. We provide a test cock 294 between valves 292 and 296. We connect the high gas pressure switch 298 to the outlet of valve 296. Respective modulating valves 304 and 305 are connected by a common linkage 306 and are adapted to be driven by a medium torque operator 300 to supply fuel to burner sections 54:: and 54b. We connect respective gauges 308 and 309 to the burner section inputs. A solenoid-operated blocking valve normally prevents flow of fuel to valve 305.

Referring now'to FIGS. 7A and 78, we have shown one form of electrical circuit which can be used to control our incinerator hot oil recovery system. A suitable source of three-phase power 310 is connected to the exhaust motor 36 designated as M-l in FIG. 7A by contacts 1MR-2 to 1MR-4. Contacts 2MR2 to 2MR4 connect the pressure fan motor 64 designated as M2 in FIG. 7A to the source 310. Normally open switch contacts 3MR2 to 3MR4 are adapted to be closed to connect a motor M3 associated with the main oil pump 172 to the source 310. Contacts 4MR2 to 4MR4 are adapted to be closed to energize a motor M4 associated with the auxiliary oil circulating pump 178. Contacts 5MR2 to 5MR4 close to connect a motor M5 associated with the transfer pump 94 to the source 310.

A transformer indicated generally by the reference character 312 connects two phases of the source'310 to the contacts of manually-operable, normally-open switches 18 and 2S which are ganged and which may be actuated to couple power to the control circuit onductors 314 and 316. When the system is to be set'into operation, a push button switch FBI is adapted to be closed to energize a winding lMRthrough a normally closed stop push button PB2. Winding lMR'when energized closes contacts lMR-l to provide a holding circuit for winding IMR, bypassing push button switch PBl. At the same time switch contacts 1MR-2 to lMR-4 close to energize Ml. Further,-in response to fan flow circuit closes.

energization of winding LMR, a switch lMR-S in the' closed stop push button switch PB4LEnergiza'tion of winding 2MR provides a holding circuit for itself by closing switch 2MR-1 which by-pas'ses push button switch PB-3. Switches 2MR-2 to 2MR4 close to energize motor M-2 which drives the pressurizing fan 62 and a switch 2MR-5 in the fan flow circuit closes.

If the exhaust fan is working properly the flow of air closes an exhaust air flow switch FSl to light a lamp L1 to indicate that the exhaust air is on. In addition, it may energize a winding lCR for use with the press equipment with which our system is associated. Since the auxiliary equipment does not per se form part of our invention, it will not be described in detail. When the exhaust air flow is established, a switch FS2 closes to light a lamp L2 indicating that the pressurizing air flow has been established. At the same time power is coupled to one contact of the low gas pressure switch LGPS designated as 282 in FIG. 5. If gas pressure is above a predetermined low pressure, switch LGPS closes. So long as gas pressure is not above a predetermined high pressure, a gas high pressure switch HGPS, designated by reference numeral 298 in FIG. 5, remains closed. Under these circumstances when switch FS] and FS2 close the gas pressure indicator lamp L3 is lit.

Once the exhaust air flow and the pressurizing air flow have been established, the circulating oil flowis initiated. A normally-open push button switch PBS is closed to complete a circuit for relay winding 3MR through a normally-closed stop push button switch PB6 and through the normally-closed oil high pressure switch OHPS indicated by reference numeral 168 in FIG. 4. Winding 3MR completes its own holding circuit through contacts 3MR-l which by-pass push button switch PBS. At the time at which winding 3MR is energized, a lamp L4 lights to indicate that the oil circulating pump motor is on. Energization of winding 3MR also closes contacts 3MR-2 to 3MR-4 to energize the motor M3 associated with pump 172. Winding 3MR further closes normally-open switch contacts 3MR-5 in the oil pressure indicator circuit. When the flow of oil is established, an oil pressure switch OPS, designated as 136 in FIG. 4, closes to complete the circuit of lamp L5 to indicate that oil flow has been established.

If the main oil pump I72 fails to operate for any reason, the auxiliary or standby pump 178 is set into operation by closing switch PB7 to energize winding 4MR through stop push button switch PBS and the oil high pressure switch OHPS and to light lamp L6 indicating that the standby pump motor has been energized. Winding 4MR completes its own holding circuit through contacts 4MR-l and closes contacts 4MR-2 to 4MR-4 to energize motor M4 associated with pump 178. Again when oil circulation has been established, switch OPS closes to energize lamp LS through a switch 4MR-5 associated with relay winding 4MR to indicate that oil pressure has been established.

Energization of the lamp L5 in the manner described also completes a circuit to a conductor 318 to energize the ignition control circuit 320 of our system which is enclosed in broken lines in FIG. 7A. Circuit 310 may be of any suitable type known to the art which is capable of performing the functions to be described hereinbelow. A specific type of such a circuit is made and sold by Protection Controls Inc. of Skokie, Illinois under the name Protectofier". When power is applied to the circuitry 320 in the manner described, the primary winding 322 of a transformer is energized to couple power to two transformer secondaries 324 and 326. We con nect a cam switch CS-I normally occupying the position shown, a normally-closed relay switch 2CR-l, a resistor 328, secondary winding 326, a bimetallic element 330, a switch element 332 adapted to be operated by the bimetallic element 330, and a relay winding 3CR in series between conductor 318 and the conductor 316.

As a result, upon the application of power to the circuit 320, the winding 3CR is energized. When that occurs, normally-open switch contacts 3CR-l close to prepare a circuit which is complete through the thermostatic element 330 when switch CS-2 closes. At the same time normally-open switch contacts 3CR-2 and 3CR-3 close to complete the circuit of a timer motor TM through a normally-closed switch 2CR-2 associated with a relay winding 2CR.

When the timer motor TM begins to drive, it first moves switch CS-l from the position shown to an alternate position to complete the circuit of the timer motor to by-pass switches 3CR-2, 3CR-3, and 2CR-2. Switch 3CR-2, however, continues to maintain a holding cir cuit for winding 3CR through switch 3CR-2 to the common terminal of the bimetallic element 330 and the switch element 332. At the end of a purge cycle sufficient to clear the incinerator of vapors, such for example as a period of one minute, switch CS-2 is closed by timer motor TM to complete a circuit across secondary winding 326 and including switch 2CR-1, a resistor 328, element 330, switches 3CR-l and CS-2 to insure that current is flowing through the bimetallic element 330.

Motor TM then closes switch CS3 to energize the supply valve solenoid Sl associated with valve 268 to initiate the flow of fuel to the burner pilots. At the same time power is applied to the ignition transformer IT to actuate a spark device 336 to ignite the pilot. When the flame is established, a flame sensing device 338 com pletes a circuit for winding 2CR through the secondary 314. When the winding 2CR is energized, contacts 2CR-1 in the safety check circuit open. Contacts 2CR-2 in the timer motor starting circuit open to permit the motor to stop when it has returned to the zero position at which cam switch CS1 contacts the upper contacts indicated in FIG. 7A. When the winding 2CR is energized in the manner described, contacts 2CR-3 open to interrupt the ignition circuit and contacts 2CR-4 close to by-pass the cam switch CS3 to hold the solenoid S-l energized. Finally, contacts 2CR-5 close to energize lamp L7 to indicate that the pilot is lit, At the same time control power is applied to a conductor 340.

A high temperature limit switch assembly 342, which receives power from the conductors 314 and 316, maintains the circuit of a relay winding 4CR so long as the temperature of the thermocouple 344 in the stack is below a predetermined temperature and so long as the high oil temperature limit switch OI-ITS, designated by reference character 146 in FIG. 4, and connected between conductor 340 and the control input of the limit switch assembly 342 remains closed. The high temperature limit switch assembly 342 may be of any suitable type known to the art, such for, example as a Model 28l-L high temperature limit switch sold by Barber Coleman Company. Winding 4CR when energized closes switches 4CR-l and 4CR-2.

Next, a push button switch PB9 is closed to complete the circuit of a winding SCR through a shut-off push button switch PBIO and the switch 4CR-1. When energized, winding SCR closes contacts SCR-l to provide a holding circuit which by-passes switch PB9. In addition, switch contacts 5CR-2 close to apply power to the winding S2 of the safety shut-off valve, designated by reference character 284 in FIG. 5. We provide ganged double-pole, double-throw switches VSl and VS2 associated with the winding S2. The moveable contact of switch VSI normally engages the lower of the two contacts shown in the figure to energize a warning horn 346 through normally-closed switch contact 6CR-l. When the winding S2 is energized, the moveable contact switch VSl moves into engagement with the upper contact to interrupt the circuit of the warning horn 346 and to establish a circuit for a lamp L8 through switch 4CR-2 to indicate that the burner is on. A normally-open push button switch PBll connected in series with a relay winding 6CR between the lower contact of switch VSl and conductor 316 is adapted to be actuated to energize winding 6C R to open contact 6CR-l to silence the horn 346 and to close contact 6CR-2 to light a lamp L9 indicating trouble. This is done in the event that the horn is not automatically silenced after a period of time in operation of the system.

We connect a high fire selector switch HFS in series with a winding 7CR between the upper contact of switch VS2 and the conductor 306. When a high fire is desired, switch HFS is closed so that winding 7CR is en* ergized when the moveable contact of switch V52 engages the upper of the stationary contactsshown in the drawing. When that occurs a lamp L connected in parallel with winding 7CR lights to indicate that high fire is on.

A temperature Controller assembly 348, of any suitable type known to the art, has power input terminals connected to the lines 314 and 316. A thermocouple 350 located in the exhaust stack provides a control input signal to the assembly 340. This temperature controller 348 may, for example, be a Barber Coleman Model 533I-I-1 temperature controller. The Model 533H-1 controller accepts the output of a standard thermocouple and produces an output signal which may be fed to any suitable controller. In our particular arrangement, output conductors 352 and 356 from the unit 348 provide a signal adapted to activate a suitable control device such as a Barber-Coleman Model No. 655A Intermediate Controller, which accepts an input of 2 to 12 ma, and provides proportional contact closures by an output relay for positioning a suitable operator. Since the specific construction of the-intermediate controller does not per se form part of our invention, it will not be described in detail.

In the particular embodiment of our control circuit shown, the intermediate controller 356 is adapted to actuate the gas valve operator 300 which may, for example, be a Barber-Coleman medium torque operator such as that described in Barber-Coleman Instruction Sheet l321/lN-l-5. As is described therein, the medium torque operator includes a heavy duty reversible shaded pole motor. It includes a built-in potentiometer the wiper arm of which is driven by the output shaft to provide a feedback signal to the intermediate controller 356. Its limits are governed by cam-operated switches. Since the details of the operator 300 do not, per se form part of our invention, they will not be described in detail.

Both the intermediate controller 356 and the operator 300 receive power from lines 314 and 316. A relay winding 7CR, adapted to be energized when the high fire switch HFS has been closed and when switch VS2 closes, is adapted to close normally open switch contacts 7CR-1 and 7CR-3 and to open normally closed switch contacts 7CR-2. Contacts 7CR-2 normally set the operator to drive to the lower control limit at which a minimum of gas is supplied to the burners uncler low fire conditions. When high fire has been selected so that winding 7CR is energized, 7CR2 opens and 7CR-1 and 7CR-3 close to apply the control output current from controller 356 to the operator 300 to permit the operator to operate bidirectionally in response to the control signal. Conductors 358 provide the feedback from the operator to the intermediate controller.

A relay winding 8CR associated with the temperature controller 348 remains de-energized until under high fire conditions it is energized to open normally-closed switch contacts SCR-l. Under these conditions a winding 9CR normally is energized to open normally-closed contacts 9CR-l and to close normally-open contacts 9CR-2, associated with a damper operator 360 which may be a Barber-Coleman operator of the same type as is operator 300. We arrange the operator 360 so that it is at one limit of its movement under low fire conditions and at the other limit under high fire conditions. With the operator 360 receiving power from lines 314 and 316, contacts 9CR-l set the controller to drive to the minimum limit. When winding 9CR is de-energized 10 under high fire conditions, contacts 9CR-l open and contacts 9CR-2 close to cause controller 360 to drive to its maximum limit. We may provide a limit switch 362 on the exhaust fan inlet vortex to light a lamp L1] to indicate the full open position.

Referring now to FIG. 8, we have illustrated a lower explosion limit control arrangement which we incorporate in our incinerator hot oil recovery system. In a standard press line consisting of six standard dryers, one extended dryer and one two-zone overprint dryer, any combination of the dryers can run at any one time. In addition, it is possible to have ink laydowns in any section of the press which are very light. Under either of the two conditions or both of the two conditions just mentioned, it is desirable that the system be so controlled as not to heat excess air in the incinerator, thus wasting fuel. We provide the arrangement of FIG. 8 to avoid the waste of fuel incident to heating excess air when little or no solvents are being evaporated in one or more of the press sections.

Referring nowto FIG. 8 in which we have shown only four of the nine dryers of a standard press line, the hood 22 of each of the units 14, 16, 18 and 20 is connected to the common line 24 by a respective line 364 in which we place a baffle 366. Also associated with each of the press units is a device 368 of a type known to the art which samples the air passing through line 364 and which determines the quantity of solvent in the air. Typical devices of this type are marketed by Avion Instrument Company and by Mine Safety Equipment Company. In response to the amount of vapor in the air being sampled, the device 368 puts out a pneumatic signal on a line 372 which is fed to an actuator 374 to position an arm 376 as a measure of the quantity of solvent in the air being sampled. Arm 376 is connected by a linkage 378 to the baffle 366 so as to open the baffle as more solvent is in the air being removed from the press hood. We connect line 24 to a static pressure controller adapted to put out a pneumatic signal to an actuator 382 in response to the static pressure in line 24. Actuator 382 drives an arm 384 connected by a linkage 386 to drive the baffle 388 in line 24 to control the volume of air drawn by the fan 34.

In operation of the lower explosion limit control illustrated in FIG. 8, the controller 380 first is set for a pressure of approximately 2 inches water column with full fan volume with the damper 388 open and with all the dampers 366 open. Next, the dryer dampers 366 are .closed, in which condition each of the dampers allows a flow of approximately 600 standard cubic feet per minute through its associated dryer. When the dryer dampers 366 are thus closed, static pressure in the main duct goes up to, for example, 5 inches W.C. since the fan is running at constant speed. When the static pressure thus rises above the static pressure for which controller 380 is set, air is fed to the actuator or air motor 382 associated with the fan damper 388 to close the damper to bring the static pressure back to 2 inches W.C., thereby reducing the fan volume.

When the solvent concentration in any particular unit builds up to the set point of the associated controller 368 such, for example, as say 40%, the controller sends an air signal through its line 372 to the air motor 374 to move the damper 366 from its closed position toward its open position. This operation allows more air to be pulled from the dryer to maintain the set lower explosion level.

When the dryer dampers 366 begin to open in the manner described, the static pressure in the common duct 24 drops to, for example 1 inch W.C., so that controller 380 moves damper 388 toward its open position to the set point static pressure of 2 inches W.C.,

thus enabling the fan 34 to draw more volume from the dryers 22. In thismanner the incinerator volume is maintained at the exact level to maintain the set lower explosion limit and fuel is not wasted by handling large volumes of air when little solvent is being evaporated in the various press units. It will readily be appreciated that the static pressure values and percent of solvent value given above are merely exemplary and will vary from installation to installation.

The operation of our incinerator hot oil recovery system will be apparent from the detailed description hereinabove. To set the system into operation, the line switches 1S and 2S are closed to apply power to the control circuit. Next FBI is actuated to energize winding lMR to connect the exhaust fan motor M1 to the source of power. Push button PB3 is closed to energize 2MR to start up the pressure fan motor. If both of these fans are properly in operation, lamps L1 and L2 light. Next the oil pump motor M3 is started and lamp L5 lights as long as the oil pressure is satisfactory. In addition, power is applied to the ignition control circuit to light lamp L7 when the pilot is lit and to apply control power to the remainder of the circuit.

When power is applied to the circuit, the alarm horn 346 is energized and remains on until the safety shutoff valve switches VSl and VS2 operate or until push button PBll is actuated to stop the horn and to light the trouble lamp. The system normally operates under low fire conditions. When high fire conditions are required, switch HFS is closed to energize winding 7CR to render the operator 300 capable of operating in both directions. At the same time the damper operator 360 is set to the high fire condition.

Contaminants drawn into the combustion chamber of the incinerator are burned and the resultant harmless products pass upwardly through the stack 68. At the same time the circulating oil system circulates the oil from the various press units through the heat exchanger coils in the heat exchanger 78. The harmless products of combustion which are passing upwardly through the stack 68 heat the oil which is then returned to the units whereat this oil is brought into heat exchange relationship with fresh incoming air to heat the same for the drying process required at the press units. As is pointed out hereinabove, various safety features are incorporated in the system to avoid damage to the equipment and injury to personnel.

It will be seen that we have accomplished the objects of our invention. We have provided an incinerator hot oil recovery system which is especially adapted for use in an installation in which drying air must be heated and in which contaminant-laden air must be disposed of. Our incinerator hot oil recovery system disposes of contaminant-laden air without polluting the atmosphere. Our system eliminates the need for a separate source of energy to heat air drying oil in installations such as color presses, for example, which require drying air. Our system is extremely efficient for the result achieved thereby.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinationsv out departing from the spirit of our invention. It is,

therefore, to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, what we claim is: I

1. Apparatus for use with an installation comprising a plurality of individual drier units at each of which drying air is to be heated andfrom each of which contaminant laden air is to be removed including in combination, an incinerator for burning contaminants in air fed thereto to reduce said contaminants to harmless byproducts in hot relatively uncontaminated air, a first heat exchange at said incinerator for bringing a heat transfer medium into heat exchange relationship with said hot uncontaminated air to heat said transfer medium, a plurality of second heat exchangers located respectively at said drier units for bringing said transfer medium into heat exchange relationship with drying air at said units, means for circulating said transfer medium through said first and second heat exchangers, a common air duct leading from said installation to said incinerator, respective individual air ducts leading from said units to said common duct, a fan for drawing contaminant laden air from said units through said individual ducts to said common duct and from said common duct to said incinerator, respective means responsive to the levels of contaminants in air in said individual ducts for regulating the respective air flows through said individual ducts to said common duct, and means responsive to the pressure of air in said common duct for regulating the flow of air from said commonduct to said incinerator.

2. Apparatus as in claim 1 in which said circulating means includes a circulating line running between said first heat exchanger and said second heat exchangers, said apparatus including a normally closed line adapted to be opened to cause said circulating medium to bypass said second heat exchangers and means responsive to the pressure of said medium in said circulating line for opening said normally closed by-pass line.

3. Apparatus as in claim 1 in which said circulating system includes a common feed pipe leading from said first heat exchanger to said installation and a common return pipe leading from said installation to said first heat exchanger, a normally closed by-pass pipe connecting said feed and return pipes, and means responsive to the flow of said medium through said return pipe for openingsaid by-pass pipe to maintain a substantially constant flow of said medium through said first heat exchanger.

4. Apparatus as in claim 1 including respective means for regulating the temperature of dryingair at each of said drier units.

5. Apparatus as in claim 4 in which each of said regulating means comprises means for sensing the temperature of drying air at one of said .units and means responsive to said sensing means for controlling the flow of said medium from said first heat exchanger to said installation. I Y

6. Apparatus as in claim 1 in which said incinerator includes a main exhaust for said hot uncontaminated air, and an auxiliary exhaust for said hot uncontaminated air. said first heat exchanger being located in said main exhaust, said system including means responsive to the temperature of said heating medium for regulating the relative amounts of said hot uncontaminated air flowing through said main and auxiliary exhausts.

7. Apparatus as in claim 1 in which said incinerator has a high fire state and a low fire state, said apparatus including means responsive to the state of said incinerator for controlling the flow of contaminated air from said installation to said incinerator.

8. Apparatus for use with an installation comprises a plurality of individual drier units, at' which drying air is to be heated and from which air containing contaminants is to be removed including in combination, an incinerator comprising a combustion chamber, a burner in said combustion chamber, means for supplying burner fuel in said burner, a main exhaust passage and an auxiliary exhaust passage, said incinerator adapted to burn contaminants in air fed thereto to reduce said contaminants to harmless by-products in hot relatively uncontaminanted air adapted to flow out of said main and auxiliary exhaust passages, means for feeding contaminated air from said installation to said incinerator, a first heat exchanger located in said main exhaust passage, a second heat exchanger at each said individual drier units, a circulating system including said first and second heat exchangers for carrying a heat transfer medium into heat exchange relationship with hot relatively uncontaminated air moving through said exhaust passage to heat said medium and through said second heat exchanger to heat drying air at said installation, means for sensing the temperature of said medium in said circulating system, and means responsive to said sensing means for regulating the relative amounts of said hot relatively uncontaminated air flowing through said main auxiliary exhaust passages.

9. Apparatus as in claim 8 in which said circulating system includes a feed pipe leading from said first heat exchanger to said installation and a return pipe leading from said installation to said first heat exchanger, a normally-closed by-pass connecting said feed and return pipes, and means responsive to flow of said medium through said return pipe for opening said by-pass to maintain a substantially constant flow of said medium through said first heat exchanger.

10. Apparatus as in claim 8 including means for sensing temperature of said medium as it leaves said first heat exchanger and means responsive to said temperature sensing means for interrupting the flow of burner fuel to said burner at a predetermined high temperature of said medium.

11. Apparatus as in claim 8 in which said circulating system includes a pump, a motor for driving said pump and means for energizing said pump, said apparatus including means for sensing the pressure of said medium, and means responsive to said pressure sensing means for deenergizing said pump.

12. Apparatus as in claim 8 in which said circulating system includes a feed pipe leading from said first heat exchanger to said installation and a return pipe leading from said installation to said first heat exchanger, a normally closed by-pass connecting said feed and return pipes, and means responsive to flow of said medium through said return pipe for opening said by-pass to maintain a substantially constant flow of said medium through said first heat exchanger.

13. Apparatus as in claim 8 in which said incinerator has a high fire and a low fire condition, first means responsive to said high fire condition for increasing the flow of fuel to said burner and second means responsive to said high fire condition for increasing the flow of contaminated air to said incinerator.

14. Apparatus as in claim 13 including means responsive to the temperature in said combustion chamber for actuating said means responsive to said high fire condition. 1

15. Apparatus as in claim 8 in which said means for feeding contaminated air from said installation comprises means responsive to the level of contaminants in the air at said installation for regulating the flow of air from said installation to said incinerator.

16. Apparatus as in claim 15 in which said means for feeding contaminated air from said installation to said incinerator comprises a duct, a fan for feeding air from said du'ctto said incinerator and means responsive to the pressure of air in said duct for regulating the flow of air from said duct to said fan.

17. Apparatusas in claiml6 in which said means for regulating the flow of air from said duct to said fan includes a baffle between said duct and said fan and means responsive to an increase in the pressure in said duct for moving said baffle toward an open position.

18. Apparatus as in claim 17 in which said means for regulating'the flow of air from said installation to said duct comprises a second baffle and means responsive to an increase in the level of contaminants in the air at said installation for moving said second baffle toward an open position. 

1. Apparatus for use with an installation comprising a plurality of individual drier units at each of which drying air is to be heated and from each of which contaminant laden air is to be removed including in combination, an incinerator for burning contaminants in air fed thereto to reduce said contaminants to harmless byproducts in hot relatively uncontaminated air, a first heat exchange at said incinerator for bringing a heat transfer medium into heat exchange relationship with said hot uncontaminated air to heat said transfer medium, a plurality of second heat exchangers located respectively at said drier units for bringing said transfer medium into heat exchange relationship with drying air at said units, means for circulating said transfer medium through said first and second heat exchangers, a common air duct leading from said installation to said incinerator, respective individual air ducts leading from said units to said common duct, a fan for drawing contaminant laden air from said units through said individual ducts to said common duct and from said common duct to said incinerator, respective means responsive to the levels of contaminants in air in said individual ducts for regulating the respective air flows through said individual ducts to said common duct, and means responsive to the pressure of air in said common duct for regulating the flow of air from said common duct to said incinerator.
 2. Apparatus as in claim 1 in which said circulating means includes a circulating line running between said first heat exchanger and said second heat exchangers, said apparatus including a normally closed line adapted to be opened to cause said circulating medium to by-pass said second heat exchangers and means responsive to the pressure of said medium in said circulating line for opening said normally closed by-pass line.
 3. Apparatus as in claim 1 in which said circulating system includes a common feed pipe leading from said first heat exchanger to said installation and a common return pipe leading from said installation to said first heat exchanger, a normally closed by-pass pipe connecting said feed and return pipes, and means responsive to the flow of said medium through said return pipe for opening said by-pass pipe to maintain a substantially constant flow of said medium through said first heat exchanger.
 4. Apparatus as in claim 1 including respective means for regulating the temperature of drying air at each of said drier units.
 5. Apparatus as in claim 4 in which each of said regulating means comprises means for sensing the temperature of drying air at one of said units and means responsive to said sensing means for controlling the flow of said medium from said first heat exchanger to said installation.
 6. Apparatus as in claim 1 in which said incinerator includes a main exhaust for said hot uncontaminated air, and an auxiliary exhaust for said hot uncontaminated air, said first heat exchanger being located in said main exhaust, said system including means responsive to the temperature of said heating medium for regulating the relative amounts of said hot uncontaminated air flowing through said main and auxiliary exhausts.
 7. Apparatus as in claim 1 in which said incinerator has a high fire state and a low fire state, said apparatus including means responsive to the state of said incinerator for controlling the flow of contaminated air from said installation to said incinerator.
 8. Apparatus for use with an installation comprises a plurality of individual drier units, at which drying air is to be heated and from which air containing contaminants is to be removed including in combination, an incinerator comprising a combustion chamber, a burner in said combustion chamber, means for supplying burner fuel in said burner, a main exhaust passage and an auxiliary exhaust passage, said incinerator adapted to burn contaminants in air fed thereto to reduce said contaminants to harmless by-products in hot relatively uncontaminanted air adapted to flow out of said main and auxiliary exhaust passages, means for feeding contaminated air from said installation to said incinerator, a first heat exchanger located in said main exhaust passage, a second heat exchanger at each said individual drier units, a circulating system including said first and second heat exchangers for carrying a heat transfer medium into heat exchange relationship with hot relatively uncontaminated air moving through said exhaust passage to heat said medium and through said second heat exchanger to heat drying air at said installation, means for sensing the temperature of said medium in said circulating system, and means responsive to said sensing means for regulating the relative amounts of said hot relatively uncontaminated air flowing through said main auxiliary exhaust passages.
 9. Apparatus as in claim 8 in which said circulating system includes a feed pipe leading from said first heat exchanger to said installation and a return pipe leading from said installation to said first heat exchanger, a normally-closed bypass connecting said feed and return pipes, and means responsive to flow of said medium through said return pipe for opening said by-pass to maintain a substantially constant flow of said medium through said first heat exchanger.
 10. Apparatus as in claim 8 including means for sensing temperature of said medium as it leaves said first heat exchanger and means responsive to said temperature sensing means for interrupting the flow of burner fuel to said burner at a predetermined high temperature of said medium.
 11. Apparatus as in claim 8 in which said circulating system includes a pump, a motor for driving said pump and means for energizing said pump, said apparatus including means for sensing the pressure of said medium, and means responsive to said pressure sensing means for deenergizing said pump.
 12. Apparatus as in claim 8 in which said circulating system includes a feed pipe leading from said first heat exchanger to said installation and a return pipe leading from said installation to said first heat exchanger, a normally closed by-pass connecting said feed and return pipes, and means responsive to flow of said medium through said return pipe for opening said by-pass to maintain a substantially constant flow of said medium through said first heat exchanger.
 13. Apparatus as in claim 8 in which said incinerator has a high fire and a low fire condition, first means responsive to said high fire condition for increasing the flow of fuel to said burner and second means responsive to said high fire condition for increasing the flow of contaminated air to said incinerator.
 14. Apparatus as in claim 13 including means responsive to the temperature in said combustion chamber for actuating said means responsive to said high fire condition.
 15. Apparatus as in claim 8 in which said means for feeding contaminated air from said installation comprises means responsive to the level of contaminants in the air at said installation for regulating the flow of air from said installation to said incinerator.
 16. Apparatus as in claim 15 in which said means for feeding contaminated air from said installation to said incinerator comprises a duct, a fan for feeding air from said duct to said incinerator and means responsive to the pressure of air in said duct for regulating the flow of air from said duct to said fan.
 17. ApparaTus as in claim 16 in which said means for regulating the flow of air from said duct to said fan includes a baffle between said duct and said fan and means responsive to an increase in the pressure in said duct for moving said baffle toward an open position.
 18. Apparatus as in claim 17 in which said means for regulating the flow of air from said installation to said duct comprises a second baffle and means responsive to an increase in the level of contaminants in the air at said installation for moving said second baffle toward an open position. 